It is known to provide a preprogrammed machine, operated by numerical control (CNC or Computer Numerical Control) or other computerized digital programming technology for the production of bores or holes in I-beams and like structural shapes, especially heavy steel structural shapes, also known as profiles. Such a machine can be used to provide the holes in the flanges and/or web of the structural shape through which bolts or rivets may be inserted in the assembly of the I-beam with other beams and the like.
A machine of this type can comprise a portal-like frame having vertical frame members and a horizontal yoke which can span opposite heads of the I-beam over the latter. Roller means or the like can be provided to guide the frame along the I-beam or the I-beam through the frame and a feed unit can be provided between the frame and the I-beam to effect such relative displacement longitudinally of the I-beam.
To provide an output of this relative displacement, displacement measuring means is provided which can have a digital output generating signals for the programming unit. At least one vertical member and, if desired, the horizontal member of the frame are provided with carriages for vertical (up and down) and horizontal (back and forth) movement of drilling units which can produce the aforementioned holes.
The displacement measuring unit can be located ahead of the boring carriages or tools to provide an input representing the position of the assembly vis-a-vis the I-beam to permit drilling of the respective holes at the appropriate locations.
This apparatus has been found to be highly successful because it allows extremely precise relative displacement of I-beam and the frame, exact control of the drills and the positioning of the tools and, in general, a completely automatic robot-like or automated operation under the digital control of the programmable controller.
The feed unit and the displacement measuring unit can be embodied in various ways and, for example, the displacement measuring unit can comprise one or more measuring discs which can be rotated upon relative displacement of the frame and workpiece, to generate the position indicating signals. One of these discs can be located ahead of the tools and another behind the tools and, of course, both are connected to the programming unit for the control of the single feed unit (see German printed application--Auslegeschrift--DE-AS No. 27 42 072).
Frequently, however, it is necessary to provide so-called blockouts, cutouts or other shapes or contours in a steel beam which has transversely been provided with such holes or even which may remain free from such holes, e.g. for a building assembly of a structure from the steel beams. Such openings or patterns can include throughgoing openings through which conduits or other elements can pass or through which welding can be effected or even bevels, chamfers and the like. In the past such blockouts or cutouts have required material removal by milling or other machining techniques and the formation of them was effected entirely independently from the formation of the holes previously mentioned.
While I do not know if in practice any boring machines of the type described have been utilized for producing such cutouts or blockout patterns, it is possible to conceive of a modification of the standard boring machine described above in which the boring tools are replaced by milling cutters or other material removal tools capable of producing such blockouts. However, additional means provided for this purpose would double the cost at least of a plant for fabricating I-beams and even the modification of the boring machine would require complex control technology and might not be successful.